Larvicidal tests

Bloassays. House fly larvicide tests required a modified (1 7 ), semi-defined (1J5) synthetic diet to rear larvae. A brief description of the test method follows. Fifty freshly deposited eggs (from NAIDM strain of flies) were placed on top of a gel matrix comprised of water (8 ml), synthetic house fly diet (1.5 g), vitamin mixture (0.5 ml), and test compound at the required concentration. Resulting larvae were allowed to develop in the gel (held at 27°C for the duration of the test) to the pupal stage and pupae that survived treatment were counted. From counts, percent inhibition of pupation was calculated. Scoring system (based on percent inhibition of pupation) 0, normal... 

A brief description of the yellow fevet mosquito (Aedes aegyptl (L.)) larvicide test follows. An acetone solution (0.5 ml) containing the appropriate amount of test compound was added to a mixture of distilled water (49.5 ml), Tween 80 (25 mg), and a single pellet of rabbit chow (Ralston-Purina). Twenty late-4th instars (5-6 days posthatch) were added to this medium and the medium was Incubated at 27 C. 

Keiding, J., Jespersen, J.B. and El-Khodary, A.S. (1991) Resistance risk assessment of two insect development inhibitors, diflubenzuron and cryomazine, for control of the house fly Musca domestica. Part 1 larvicide tests with insecticide-resistant laboratory and Danish field populations. Pesticide Science, 32, 187-206. 

The testing techniques used with mosquito larvae, usually the addition of calculated quantities of the larvicide previously dissolved in a water-miscible solvent, are somewhat more comparable. However, the results here are conflicting. The A. qvxjdnmaculatus larvae are killed within 24 hours by either DDT or DFDT at concentrations somewhat... 

In the course of work on the mechanism of elimination reactions, the author and his co-workers have measured reaction-rate constants for the second-order elimination of hydrogen chloride from six dichloroethyl compounds of type Ar2CHCHCl2 and three monochloroethyl compounds of type Ar2CHCH2Cl (7). Samples of each of these materials were furnished to the Bureau of Entomology and Plant Quarantine for insecticidal testing, and the author is indebted to C. C. Deonier and I. H. Gilbert for permission to use certain of their data in this paper. The rate constants and larvicidal results are given in Table I. 

U.S. Fish and Wildlife Service (USFWS). 1968. Field Appraisal of Tests to Control Salt Marsh Mosquito with Dursban Applied as a Larvicide And Adulticide in Florida. U.S. Fish Wildl. Serv. Spec. Rep., Pesticide Field Appraisal Program, Atlanta, Georgia. Mimeo. 25 pp. 

While carrying out tests on mosquito larvicides in Florida, Burrell et al, (8) found that oils were not spreading properly on most of the waters in September, and that some type of inhibiting biological film had formed on these breeding areas after control operations had been initiated early in the summer. They compared the spreading properties of Triton X-100 and of a Span 20-Tween 20 mixture (equal parts when used in No. 2 fuel oil) the results are given in Table II. 

Industrial firms should be encouraged to develop test methods for accelerated storage stability determination for bacterial larvicides. 

The industry should be encouraged to evaluate the applicability of CIPAC and WHO test methods for quality control of bacterial larvicides. 

Industry should provide the relevant test methods to determine the identity and content of the active ingredients of bacterial larvicide products. 

The azido derivative 683 (CGA 19255) had herbicidal and even better insecticidal activity. 683 prevented the development of the larvae of the house fly (Musca domestica) it was tested successfully as a poultry feed-through lar-vicide " . 684 (CGA 72622 cyromazine, Larvadex ), a metabolite of 683 23,824 proved to be better suitable as a larvicide " . It inhibited growth of a great variety of Diptera insect larvae (e.g. house fly, yellow fever mosquito, face fly, sheep blowfly, fall army worm). Additionally, 684 was used as anthelmintic . 684 is applied as a food additive for domestic or livestock animals or by spraying it on manure surface. Larvicidal properties of formamido " and formamidino derivatives of 684 have been tested. The bacterial degradation of 684 was investigated . ... 

Chiricanine A (73), longistylines C, D, and 3,5-dimethoxystilbene showed toxic properties against larvae of the yellow fever-transmitting mosquito Aedes aegypti. 3,5-Dimethoxystilbene was found to be as potent as rotenone in larvicidal dilution tests [49]. 

In domestlca tests, only dithiocarbamates , 32, 33, 38, 39, 43, and 43 were larvicidal all caused 100% mortality- to immatures when incorporated in a larval diet at 100 ppm. At 10 ppm none of the compounds were active. 

Again, dithiocarbamates were prominent when tested as larvicides against P. interpunctella. While 12,... 

Although none of the compounds tested were larvicidal against S. frugiperda. several compounds (mostly dithiocarbamates) inhibited reproduction of adults that survived the larval treatment. For example, adults that emerged from a larval medium, dosed with 32, 34, 35, 41. y, or 42 at 1 00 ppm, oviposited after mating, but eggs failed to hatch. In addition to preventing egg hatch,... 

Five of these were effective larvicides. Structure-activity correlations defined for this series of compounds may serve as a useful guide for future development of hydrazine-derived larvicides. Little information was gained in Musca tests to determine how 1, and related compounds work (early instars reared on a diet containing i appeared to molt normally but vigor and food consumption were severely decreased). 

In the course of development research of fungicidal heterocyclic compounds, we found acaricidal activity among N-substituted carboxamide derivatives of some 5-membered heterocyclic compounds. In order to inquire into their activity, we synthesized and tested various skeletal compounds. We found that N-cyclohexyl-4,5-disubstituted thiazolidinone carboxamides have very high ovicidal and larvicidal activity against spider mites both in Panonychus and Tetranychus species (2-3). After development research for optimization, hexythiazox was selected as one of the representative compounds and introduced into the market in 1985. It is now widely used for the control of spider mites in fruits and vegetables in Europe and North America as well as in Japan. 

Since most of the studies have been carried out on Aedes and Culex mosquitoes, it is interesting that a-terthienyl has also been tested as a potential larvicidal agent against a malaria vector with fourth-instar Anopheles gambiae in Tanzania (4). Little information on the experimental conditions was provided, but the activity of the chemical was found to be somewhat higher than that recorded with Aedes mosquitoes in Canada (3). These results were believed to compare favorably with those obtained with synthetic pyrethrins. 

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